showdown vs disagreement

showdown and disagreement both are nouns.

Word	Noun	Adjective	Verb	Adverb
showdown	Yes	No	No	No
disagreement	Yes	No	No	No

As nouns, disagreement is a hypernym of showdown; that is, disagreement is a word with a broader meaning than showdown:

showdown (noun)	disagreement (noun)
a hostile disagreement face-to-face	a difference between conflicting facts or claims or opinions
	the speech act of disagreeing or arguing or disputing
	a conflict of people's opinions or actions or characters